438 MOTIONS OF INSECTS. 
that state I have before noticed (Leptis Vermileo), will, when removed 
from its habitation, endeavour to recover it by leaping. Indeed this mode 
of motion seems often to be given to this description of larva by Pro~ 
vidence, to enable them to return to their natural station, when by any 
accident they have wandered away from it. 
Many apodous larve inhabit the water, and therefore must be furnished 
with means of locomotion proper to that element. To this class belongs 
the common gnat (Culex pipiens), which, being one of our greatest tor- 
ments, compels us to feel some curiosity about its history. Its larva is a 
very singular creature, furnished with a remarkable anal apparatus for 
respiration, by which it usually remains suspended at the surface of the 
water. If disposed to descend, it seems to sink by the weight of its body ; 
but when it would move upwards again, it effects its purpose by alternate 
contortions of the upper and lower halves of it, and thus it moves with 
much celerity. The lamin or swimmers, which terminate its anus’, are 
doubtless of use to it in promoting this purpose. It does not, that I ever 
observed, move in a lateral direction, but only from the surface downwards, 
and vice versé.—Another dipterous larva (Corethra culiciformis), which 
much resembles that of the gnat in form, differs from it in its motions and 
station of repose ; for, instead of being suspended at the surface with its 
head downwards, it usually, like fishes, remains in a horizontal position in 
the middle of the water. When it ascends to the surface, it is always by 
means of a few strokes of its tail, so that its motion is not equable, sed 
per saltus. It descends again gradually by its own weight, and regains its 
equilibrium by a single stroke of the tail.2—A well-known fly (Stratyomis 
Chameleon), in its first state an aquatic animal, often remains suspended, 
by its radiated anus, at the surface of the water, with its head downwards, 
But when it is disposed to seek the bottom or to descend, by bending the 
radii of its tail so as to form a concavity, it includes in them a bubble of 
air, in brillianey resembling silver or pearl ; and then sinks with it by its 
own weight. When it would return to the surface it is by means of this 
bubble, which is, as it were, its air balloon. If it moves upon the surface 
or horizontally, it bends its body alternately to the right and left, contracting 
itself into the form of the letter S ; and then extending itself again into a 
straight line, by these alternate movements it makes its way slowly in the 
water, 
I have dwelt longer upon the apodous larvae, or those that are without 
what may be called proper legs, analogous to those of perfect insects, 
because the absence of these ordinary instruments of motion is in numbers 
of them supplied in a way so remarkable and so worthy to be known; and 
because in them the wisdom of the Creator is so conspicuously, or I should 
rather say, so strikingly manifested, since it is doubtless equally conspicuous 
in the ordinary routine of nature. But aberrations from her general laws, 
and modes, and instruments of action, often of rare occurrence, impress 
us more forcibly than any thing that falls under our daily observation. 
T come now to pedete larvae, or those that move by means of proper oF 
articulate legs. ‘These legs (generally six in number, and attached to the 
underside of the three first segments of the body) vary in larva of the 
. 
1 Reaum. iv. t. 43. f. 8. nn. 2 De Geer, vi. 375. t. xxiii. f. 4, 5. 
5 Swamm. Bibl. Nat, Ud, Hill, ii. 44. b. 47. a. 
